The primary purpose of the proposed research is to determine the effects, as well as limitations, of cognitive factors on human autonomic classical conditioning. The primary autonomic measures are skin conductance response, heart rate and digital pulse volume. The primary cognitive measures include measurements of the subject's awareness of the CS-UCS relation and reaction-time to extraneous auditory probes. Both of these measures of cognitive factors are made during the conditioning session. In this way, it is possible to concurrently measure and interrelate autonomic and cognitive changes during exposure to CS-UCS pairings.